The present invention relates to cases for storing magnetic tape cassettes, and more particularly, to a cassette storage case for storing a so-called "operational" video tape cassette.
An operational video tape cassette, unlike the more common type of video tape cassette, is designed so that the reels can freely rotate when it is unloaded from the video tape recorder. Therefore, in order to prevent the magnetic tape in the video tape cassette from damage which may be caused by slackening or pulling of the magnetic tape during transport or storage of the video tape cassette, the cassette storage case should have a reel rotation preventing mechanism. Conventional cassette storage cases with such reel rotation preventing mechanisms can be divided into a first group of cassette storage cases manufactured by vacuum molding and a second group of cassette storage cases manufactured by injection molding.
These conventional cassette storage cases suffer form the following difficulties: In the cassette storage case manufactured according to the vacuum molding method, a reel rotation preventing part and the case body are vacuum molded as one unit with one and the same plastic material. In the vacuum molding method, the rotation preventing part, which engages with the reel hubs, can be made elastic by reducing its thickness. As a result, it is possible for the rotation preventing part to positively engage with the reel hubs, i.e., to positively prevent the rotation of the reel hubs. With the rotation preventing part engaged with the reel hubs, the latter cannot be deformed, even if the magnetic tape cassette is held in the cassette storage case for a long period of time. The molding apparatus is relatively low in price. In these points, employment of the vacuum molding method for manufacturing the cassette storing case is preferable. However, it is still disadvantageous in that the molding operation takes a relatively long time and accordingly the molding cost is high.
On the other hand, cassette storage cases manufactured according to the injection molding method can be classified into a first group in which the case body formed by injection molding is combined with a rotation preventing member composed of separate components such as engaging pins, and a second group in which the rotation preventing device consists of long, rigid projections formed simultaneously when the case body is formed by injection molding. The former is advantageous in that the rotation of the reel hubs can be positively prevented. However, it is disadvantageous in that, since it requires a number of separate components, a excessive number of assembly steps are required and accordingly it is high in manufacturing cost. The latter suffers from the difficulties that, when the magnetic tape cassette is stored for a long period of time, the reel hubs may be deformed, and the rotation of the reel hubs cannot be effectively prevented.